Astronomers Discover New Type of Star [VIDEO]

Astronomers have discovered a new type of variable star based on the detection of extremely small changes in the brightness of stars located in the cluster NGC 3766 (pictured here). (Photo : European Southern Observatory)

Astronomers have discovered a new type of variable star based on the detection of extremely small changes in the brightness of those located in the cluster NGC 3766.

Also known as pulsating stars, they are fairly common and are the result of complex workings in their interiors. Their existence has led to a whole new branch of astrophysics called asteroseismology, in which astronomers “listen” to these stellar vibrations in order to determine the stars’ physical properties and inner workings.

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“The very existence of this new class of variable stars is a challenge to astrophysicists,” team member Sophie Saesen said. “Current theoretical models predict that their light is not supposed to vary periodically at all, so our current efforts are focused on finding out more about the behavior of this strange new type of star.”

Discovered using the Swiss 1.2-meter Euler telescope at the European Southern Observatory’s (ESO) La Silla Observatory in Chile, the observations revealed previously unknown properties of these stars that continue to defy current theories as well as raise question about the origin of the variations.

The results are based on regular measurements of the brightness of more than 3,000 stars in the cluster over a period of seven years. They reveal how 36 of NGC 3766’s stars followed an unexpected pattern consisting of regular variations in their brightness at the level of 0.1 percent of the stars’ normal brightness.

Though somewhat hotter and brighter than the Sun, the stars are otherwise apparently unremarkable and have yet to receive a name.

The level of precision in the measurements is twice that achieved by comparable studies performed using other telescopes, and sufficient to reveal these tiny variations for the first time, according to a statement issued by the ESO.

“We have reached this level of sensitivity thanks to the high quality of the observations, combined with a very careful analysis of the data, but also because we have carried out an extensive observation program that lasts for seven years,” Nami Mowlavi, leader of the research team, said. “It probably wouldn’t have been possible to get so much observing time on a bigger telescope.”

While the cause of variability remains yet unknown, one possible clue stands out: some of the stars seem to be fast rotators, spinning at speeds more than half of their critical velocity, which refers to the threshold in which stars become unstable and start shedding material off into space.

“In those conditions, the fast spin will have an important impact on their internal properties, but we are not able yet to adequately model their light variations,” Mowlavi said.

Going forward, Mowlavi said, the scientists hope their discovery “will encourage specialists to address the issue in the hope of understanding the origin of these mysterious variations.”